Overspeed,

Remember that for two DIMMS to run in dual channel mode, they need to spaced a part by one empty DIMM, such that if bank 1 is the rightmost DIMM slot furthest from the processor, one stick is in bank 1 and the other is in bank 3, or that one stick is in bank 2 and the other is in bank 4. MSI colors their RAM slots differently than other manufacturers, which can be confusing. Make sure that one DIMM is in an orange slot and the other in the associative green slot.

As for default timings, this is normal. The motherboard will not automatically default to a 1:1 setting. Instead, it will default to the highest standard JDEC setting specified for your RAM. Now you have 1066mhz RAM, but the highest setting specified by JDEC for DDR-2 RAM is PC-6400 / 800mhz, which is why you see your RAM running at 800mhz at stock, and not 1066mhz. If you had 667mhz RAM, then you would see it run at 667mhz at stock. Secondly, the default timings for a given speed are stored in your RAM's SPD chip. This chip stores timing information for various RAM speeds at various FSB straps. 5-6-6-15-2T just happens to be the timings stored with the JDEC 800mhz speed. Now EPP, or SLI Ready memory, will store extra settings in that SPD chip, which can be activated by going into your BIOS and enabling SLI Memory. Set the SLI Memory option to 0% OC or Expert to automatically enable better timings for your given RAM speed.

As for the OC attemps, I'm sorry you're having trouble. Right now it does seem that the board works better with Conroe and Kentsfield chips. I would not recommend you OC through the Windows utility -- they tend not to work well. As for OCing through the BIOS, are you sure you have all the necessary settings disabled? Make sure that EIST and Speed Spectrums are disabled in the Cell Menu. Then go into the chip features menu where the Execute Disable Bit feature resides, press F4, and make sure that C1E is disabled and that Thermal Management is disabled. Lastly, have you tried any of the beta bioses from http://forum.msi.com.tw? The latest, 1.1B4, was released two days ago and people are finding some early success with it regarding the 45-nm chips. Before giving up, flashing to a newer BIOS is absolutely worth a try.

Good luck. Lastly, what's your PSU?